The increasing importance of personal appearance, whether in projecting a healthy, youthful or stylish image, has led to an increasing demand for cosmetics. The demand is being met by a growing number of products and suppliers with an attendant expansion in competition.
Product quality is important and is reflected by many qualities and characteristics of each product. Physical appearance of the product should be homogeneous. Any streaking, settling or separation has an adverse impact on the consumer.
A cosmetic should apply smoothly, have a good skin adhesion and a good feel. A makeup that applies unevenly, flakes, smears or feels overly dry or oily is not likely to be favorably received.
Color consistency from batch to batch is also of importance. Small variances in shade are noticeable in cosmetics and accordingly a consumer's expectation in receiving the same shade as previously obtained should be fulfilled.
Cosmetics use varying amounts of particulates including pigments, pearlescent materials, extenders, etc., dispersed in oils, waxes and emulsions. Uniform dispersion, suspension stability and particulate loading in a suspension are all factors affecting the product quality. Obviously, optimization of all is desirable.
Problems are encountered in trying to improve one or two factors without adversely affecting another or improving desired characteristics without introducing other detrimental effects.
Coating of pigments, extenders and fillers has been used to enhance dispersion of particulates by increasing hydrophobicity. Increased hydrophobicity also aids in the suspension of particulates in cosmetic preparations.
Pigments have been treated with lecithin along with lecithin component fatty acids and related fatty acids. Metal alkoxides, metal soaps and metal salts of fatty acids have been used with success.
Silicone treatment of pigments is another method of treatment and results in improved hydrophobicity. Dispersion, suspension and loading characteristics are all improved as are the water repellence and spreadability of a product incorporating the treated pigment. Enhanced skin adhesion and reduced color change on skin are also benefits of silicone treatment.
Simethicone (dimethyl polysiloxane) has been widely used as a coating and is one of the simplest, structurally, of the silicones used. However, with all the advantages associated with silicone treatment, a problem common to all the silicones results in adverse characteristics in the final product, including the failure to have extended shelf life.